Fracture resistance of incisal fragments following reattachment with different techniques in simulated crown fractures

Introduction: the aim of the present study was to evaluate and compare the effect of acid-etching and er,cr:ysgg laser treatment before the reattachment of incisal fragments in coronal fractures of permanent incisor teeth. methods: sixty-six sound human maxillary incisors were randomly divided into 3 groups (n=22). teeth were embedded in self-cure acrylic resins by leaving one-third of the crowns out,and uncomplicated crown fractures were obtained using an instron testing device. the fragments were reattached using 3 different procedures and a hybrid resin composite (z250): group i: acid etching + prime & bond nt; group ii: er,cr:ysgg + prime & bond nt; group iii: er,cr:ysgg + acid etching + prime & bond nt. the percentages of shear bond strengths were determined by comparing fracture strengths of sound and reattached teeth for 3 groups. all data were analyzed statistically with kruskal-wallis h test. results: mean fracture strengths of the reattached fragments were between 51.02% and 62.93% of that of the sound teeth in all groups. group i had significantly higher percentages of shear bond strength values (p < 0.05) when compared to group ii and group iii. no significant difference (p > 0.05) was found between group ii and group iii. conclusion: the findings of the present study show that er,cr:ysgg laser irradiation prior to the reattachment of incisal fragments has a negative effect on fracture strength.